Detection of Selected Defects in Relatively Noisy Inspection Data

1. A computer-implemented method for detecting defects on a substrate, comprising: converting information generated by inspection of a substrate into polar space; identifying periodic components in the converted information, wherein the periodic components are not periodic components due to dies formed on the substrate or structures formed in the dies; and determining if the periodic components correspond to defects on the substrate, wherein said converting, said identifying, and said determining are performed using a computer system.

2. The method of claim 1 , wherein the information comprises a wafer surface image.

3. The method of claim 1 , wherein the information comprises raw inspection data.

4. The method of claim 1 , wherein the information comprises a defect map.

5. The method of claim 1 , wherein the information comprises inspection data generated by combining two or more raw inspection data corresponding to substantially the same locations on the substrate.

6. The method of claim 1 , wherein said identifying comprises determining a one-dimensional autocorrelation function for different radiuses in the converted information and identifying the periodic components based on peaks in the autocorrelation function.

7. The method of claim 1 , wherein said identifying comprises determining an average magnitude difference function for different radiuses in the converted information and identifying the periodic components based on valleys in the average magnitude difference function.

8. The method of claim 1 , wherein said determining comprises estimating pitch and starting angle for the periodic components, defining search regions using the pitch and starting angle, and detecting defects in the search regions.

9. The method of claim 1 , wherein the defects comprise bump defects formed in concentric rings on the substrate.

10. The method of claim 1 , wherein the defects comprise epitaxial crown defects.

11. The method of claim 1 , wherein the defects comprise silicon on insulator bump array defects.

12. The method of claim 1 , wherein the defects are located in multiple rings on the substrate, and wherein more than one of the defects is located at the same radius through the multiple rings.

13. The method of claim 1 , wherein the defects are located in multiple rings on the substrate, and wherein the defects within one of the multiple rings have substantially the same angular separations between the defects.

14. The method of claim 1 , wherein the defects are located in multiple rings on the substrate, and wherein the defects within one of the multiple rings have substantially the same properties.

15. The method of claim 1 , wherein said identifying comprises performing a one-dimensional Fourier transform for different radiuses in the converted information to produce spectrums for the different radiuses and identifying peaks in the spectrums.

16. The method of claim 15 , wherein said determining comprises suppressing non-peaks in the spectrums to produce filtered spectrums, inverse transforming the filtered spectrums to a spatial domain to obtain filtered image data, and detecting defects on the substrate using the filtered image data.

17. A non-transitory computer-readable medium, storing program instructions executable on a computer system for performing a computer-implemented method for detecting defects on a substrate, wherein the computer-implemented method comprises: converting information generated by inspection of a substrate into polar space; identifying periodic components in the converted information, wherein the periodic components are not periodic components due to dies formed on the substrate or structures formed in the dies; and determining if the periodic components correspond to defects on the substrate.

18. A system configured to detect defects on a substrate, comprising: an inspection subsystem comprising one or more detectors, wherein the one or more detectors are configured to detect light from the substrate and to generate raw inspection data in response to the detected light; and a computer subsystem configured for: converting information generated by inspection of the substrate into polar space; identifying periodic components in the converted information, wherein the periodic components are not periodic components due to dies formed on the substrate or structures formed in the dies; and determining if the periodic components correspond to defects on the substrate.

19. The system of claim 18 , wherein the information comprises a wafer surface image.

20. The system of claim 18 , wherein the information comprises raw inspection data.

21. The system of claim 18 , wherein the information comprises a defect map.

22. The system of claim 18 , wherein the information comprises inspection data generated by combining two or more raw inspection data corresponding to substantially the same locations on the substrate.

23. The system of claim 18 , wherein said identifying comprises determining a one-dimensional autocorrelation function for different radiuses in the converted information and identifying the periodic components based on peaks in the autocorrelation function.

24. The system of claim 18 , wherein said identifying comprises determining an average magnitude difference function for different radiuses in the converted information and identifying the periodic components based on valleys in the average magnitude difference function.

25. The system of claim 18 , wherein said determining comprises estimating pitch and starting angle for the periodic components, defining search regions using the pitch and starting angle, and detecting defects in the search regions.

26. The system of claim 18 , wherein the defects comprise bump defects formed in concentric rings on the substrate.

27. The system of claim 18 , wherein the defects comprise epitaxial crown defects.

28. The system of claim 18 , wherein the defects comprise silicon on insulator bump array defects.

29. The system of claim 18 , wherein the defects are located in multiple rings on the substrate, and wherein more than one of the defects is located at the same radius through the multiple rings.

30. The system of claim 18 , wherein the defects are located in multiple rings on the substrate, and wherein the defects within one of the multiple rings have substantially the same angular separations between the defects.

31. The system of claim 18 , wherein the defects are located in multiple rings on the substrate, and wherein the defects within one of the multiple rings have substantially the same properties.

32. The system of claim 18 , wherein said identifying comprises performing a one-dimensional Fourier transform for different radiuses in the converted information to produce spectrums for the different radiuses and identifying peaks in the spectrums.

33. The system of claim 32 , wherein said determining comprises suppressing non-peaks in the spectrums to produce filtered spectrums, inverse transforming the filtered spectrums to a spatial domain to obtain filtered image data, and detecting defects on the substrate using the filtered image data.